[FFmpeg-cvslog] lavc/videotoolbox: fix H.264 hwaccel init issue

[Richard Kern]

> On Jun 17, 2016, at 5:31 AM, Clément Bœsch <u at pkh.me> wrote:
> 
> On Fri, Jun 17, 2016 at 03:24:10AM +0200, Rick Kern wrote:
>> ffmpeg | branch: master | Rick Kern <kernrj at gmail.com> | Wed Jun  1 21:40:22 2016 -0400| [8e47a99f576da10b2a36e33b6b9acbf1c2da7485] | committer: Rick Kern
>> 
>> lavc/videotoolbox: fix H.264 hwaccel init issue
>> 
>> Fixes VTDecompressionSessionCreate() error.
>> 
> 
> Please reference the closing Ticket next time, and mention that it's a
> regression.

ok

> 
> Also, can you elaborate on why this fix is required? What was wrong
> exactly previously, and why was it working?
> 
> It feels like it's including more than a fix.

Since ca2f19b9cc (h264: switch to h2645_parse for NAL parsing) the hwaccel wouldn’t init (when the first h.264 frame is decoded). It was the same on OS X and iOS - creating the decoder would return a “decoder malfunction” error. Apple’s suggested way to create the decoder config for h.264 decoders is CMVideoFormatDescriptionCreateFromH264ParameterSets(), and switching to this function solved the issue on OS X and iOS. A user on IRC confirmed it worked for them too.

> 
> (BTW, do you happen to be on IRC?)

Yeah, I’m rkern. I’m in the eastern US time zone and sign in to both #ffmpeg and #ffmpeg-devel.

> 
> Regards,
> 
> -- 
> Clément B.